Choose NOT NULL, UNIQUE, CHECK, primary-key, and foreign-key constraints from concrete integrity rules and verify both accepted and rejected writes.
Intermediate14 min read
SQL Fundamentals lessonRelational data foundationsPractice
UNTIMED COACHING
Practice before the pressure
Use feedback to correct the model, not merely memorize an option position.
GUIDED PRACTICE
Practice the lesson questions
Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.
20 questions balanced across the lesson's key topics
At least four explanatory diagrams or tables
Retry freely, without a timer or score
CONCEPT MODELS
See the lesson as a system
Use these visual guides to connect the key ideas before answering the questions.
Connect the roles in Constraints and Data IntegrityKeep candidate row, required value, unique identity, and parent relationship as separate roles.Verify Constraint evidenceConnect constraint evidence with its topic-specific inspection, expected outcome, and protected database boundary.